The present invention relates to a template derivative for forming an ultra-low dielectric layer, and a method of forming the ultra-low dielectric layer using the same, and more particularly, to a template derivative for forming an ultra-low dielectric layer which is capable of forming an ultra-low dielectric layer with superior mechanical strength, and a method of forming the ultra-low dielectric layer using the same.
With the requirement for high integration and high speed for semiconductor devices, the line width of metal wiring and the space between the metal wirings have been rapidly reduced over time. Particularly, with the reduction in the distance between the metal wirings, this causes an increased parasitic capacitance between the metal wirings under the interposition of an insulation layer.
Therefore, various process technologies for lowering the resistance of the metal wiring and reducing the parasitic capacitance have been studied. As part of the technology, there have been attempts to use low resistance materials, such as copper (Cu) instead of existing aluminum (Al), as the metal wiring material, and to use a low dielectric material having a dielectric constant k of approximately 3.0, instead of SiO2 having the dielectric constant k of 4.0, or fluorinated silicon glass having the dielectric constant k of 3.5, as an insulation layer material formed between the metal wirings.
Also recently, studies of ultra-low dielectric layers having a dielectric constant k of 2.2 to 2.5 are actively in progress. In relation to this, there has been an attempt for a nanotemplating method in which a thermally unstable pore generating resin, such as a porogen, is used as a nanotemplate and dispersed into an inorganic matrix, and then pores are introduced into the inorganic matrix through a high temperature heat treatment to form an ultra-low dielectric layer. At this time, it is important that the matrix containing pores should have superior mechanical and dielectric characteristics and, at the same time, the pore should have a very small size and a low connectivity.
Meanwhile, the ultra-low dielectric layer may be deposited through a chemical vapor deposition (CVD) process or a spin coating process.
In the use of the CVD process, a silicon based monomer containing a non-reactive porogen is deposited alone, or the non-reactive porogen and a matrix are co-deposited together to form the ultra-low dielectric layer. However, because the use of the CVD process is not accompanied with a chemical bonding of the two materials, i.e. the non-reactive porogen and the matrix, the use of the CVD process has the problem that it is impossible to inhibit clumping of the non-reactive porogen.
The use of the spin coating process is better than the use of the CVD process to lower the dielectric constant. However, the use of the spin coating process is problematic in that it is difficult to control pore morphology, and particularly the pores are connected with one another when the pore content exceeds 20%, and also the mechanical strength is rapidly reduced with an increase in the pore content.
Therefore, a method of forming the ultra-low dielectric layer using a reactive porogen such as cyclodextrin derivative is desired.
FIG. 1 is a view illustrating a cyclodextrin derivative.
As shown, the cyclodextrin derivative is formed using cyclodextrin as a precursor and through an allylation reaction using allylbromide and a hydrosilylation reaction using trialkoxysilane, and has a structure capped with the trialkoxysilane.
In FIG. 1, a reaction group R represents H, and R′ represents (CH2)n—SiH3.
Since this reactive porogen can undergo a sol-gel reaction with an organic silicate matrix precursor unlike the existing non-reactive porogen, such as poly-carprolactone and poly-methylmethacrylate, the ultra-low dielectric layer formed using this reactive porogen has advantages that it is superior not only in the aspect of the pore morphology but also in the aspect of the mechanical strength.
However, since the reactive porogen, such as cyclodextrin, has very low reactivity with the matrix, compared to the reactivity of the matrix itself, a clumping of the reactive porogen is generated when the porogen content is more than a specific amount, and thus the pore morphology problem cannot be solved. Particularly, when the porogen content is high, the pore size and the pore connectivity are increased and thus it is impossible to obtain the desired ultra-low dielectric layer.
Also, even in the ultra-low dielectric layer formed using the reactive porogen, such as cyclodextrin, the pore size rapidly increases resulting in the rapid decrease in the mechanical strength when the dielectric constant is uniformly and continuously lowered. Particularly, a curing process using ultraviolet rays should be followed to solve this problem, which makes the process more complicated.